The two-step biosynthesis of cyclic peptides from linear precursors in a member of the plant family Caryophyllaceae involves cyclization by a serine protease-like enzyme.

Caryophyllaceae-type cyclic peptides (CPs) of 5-12 proteinogenic amino acids occur in 10 plant families. In Saponaria vaccaria (Caryophyllaceae), they have been shown to be formed from linear peptide precursors derived from ribosomal translation. There is also evidence for such precursors in other members of the Caryophyllaceae, Rutaceae, and Linaceae families.